Abstract

Introduction In the decade since generational garbage collection was first proposed in print [Lieberman and Hewitt 83], a number of papers (including some of my own) have introduced their discussions of generational garbage collection by statements such as "between 80 and 98 percent of all newlyallocated objects die within a few million instructions", or "most newly created cells die young". While this intuition is sometimes backed up by measurements which "prove" the effectiveness of a particular generational scheme, there are very few theoretical models by which we can reasonably compare one generational scheme with another, or with non-generational schemes. We show via a counterexample that the quoted statements above are essentially meaningless, because a meaningful discussion of age-based garbage collection schemes requires the presentation of significantly more data in the form of complete object lifetime probability density functions, rather than the one or two data po

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